Special Tweaks

Special tweaks tend to do different things than upgrades. While they are free and provide very useful upgrades like Armor Piercing (vital late in the game), they come with heavy downsides. If you have plenty of money, though, the downsides can be nullified through "Remove downgrades" to retain the helpful boosts and buy even more upgrades.  Keep in mind that there are some tweaks (such as the 'Some Beggar Tweak') that cannot be upgraded, even when all the downgrades are removed.

(* Denotes upgrades that can still be upgraded, given that the downgrades are removed)

Work in progress.

Bullet weapon Tweaks

Assault Weapon

• Fire rate penalty: +25%
• Weapon spread bonus: -5% (more accurate)
• Armor Piercing damage: +15% ++
• Recoil penalty: +5%

Max upgrade of 19.

Fast Shot

• Fire rate bonus: -10%
• Weapon spread penalty: +90% (less accurate)
• Recoil penalty: +5%

Max upgrade of 5.

Bigger Caliber

• Fire rate penalty: +15%
• Reload time increased: +20%
• Max ammo penalty (primary or secondary): -15%
• Armor Piercing damage: +53% ++
• Recoil penalty: +10%

Max upgrade of 7.

Explosive weapon Tweaks

Armor Piercing Explosive*

• Blast Radius decreased: -26%
• Armor Piercing damage: +22 ++

Max upgrade of 3.

Army of Not Many*

• Clip size penalty: -15%
• Reload time increased: +70%
• Fire rate penalty: +50%
• Max ammo penalty: -40%
• Projectile speed decreased: -15%
• Armor Piercing damage: +135% ++

Max upgrade of 3. Not available on the Cow Mangler 5000.

Some Beggar Tweak

• Projectile spread angle penalty: +3 degrees
• Auto fires full clip: 1
• Can overload: 1
• Fire rate bonus (hidden): -70% (shoots faster than regular upgrades)
• Clip size penalty (hidden): -22%
• Reload time increased: +30%

One upgrade.

Some other Beggar Tweak

• Projectile spread angle penalty: 1.5 degrees
• Fire rate bonus (hidden): +8%

Max upgrade of 6. Also available on the flare guns, syringe guns, and Crusader's Crossbow.

Energy weapon Tweaks

Fast Laser Shot

• Fire rate bonus (hidden): +10%
• Reload time increased: +20%

Max upgrade of 7.

Heavy Laser Shot

• Armor Piercing damage: +15% ++
• Reload time increased: +20%

Max upgrade of 21. Exclusive to the Cow Mangler 5000.

Flamethrower Tweaks

Higher Pressure

• Flame ammopersec increased: +1
• Max ammo primary reduced: -10%
• Armor Piercing damage: +15% ++
• Afterburn damage increased: +99%

Temperature Rise

• Flame ammopersec increased: +1

• Armor Piercing damage: +15% ++

Both have max upgrades of 4.

Minigun Tweaks

Heavy Heavy Heavy Weapon

• Minigun spinup time increased: +50%
• Aiming movespeed decreased: -20%
• Armor Piercing damage: +15%
• Add recoil penalty: +5%

Max upgrade of 5.

Heavy Electric Motor

• Minigun spinup time increased: +50%
• Uses ammo while aiming: +1
• Fire rate bonus: -2.5%
• Armor Piercing damage: +38% ++

Engineer Building Tweaks

(These Tweaks are accessed from the primary weapon's tweak menu.)

(Each of these extra damage bonuses act as damage multipliers.)

Sentry Bigger Caliber

• Sentry extra damage bonus: +87.5%
• Sentry fire rate Increased: +12.5%
• Max ammo metal reduced: -11.5%

Max upgrade of 4.

Sentry Heavy Motor

• Sentry extra damage bonus: +50%
• Move speed penalty: -10%

Max upgrade of 6.

Medigun Tweaks

Doktorrrrr*

• Heal rate multiplier: +50%
• Ubercharge rate penalty: -25%

Max upgrade of 4.

Sniper Primary Tweaks

Bigger Caliber

See above for Bigger Caliber attributes.

Concentrated Fire

• Mod ammo per shot: +1
• Armor Piercing damage: +38% ++
• Add recoil penalty: +10%

Long Bow (Huntsman only)

• Fire rate penalty: +20%
• EXTRA Armor Piercing damage: +25%

Sapper Tweaks

The Red Tape

• Sapper damage penalty: 1
• Sapper degenerates buildings: +50%

One upgrade.

Melee Tweaks

Slow Swing*

• Armor Piercing: +15%
• Swing Speed: -10%

Max upgrade of 30.

Honorbound!

• Honorbound
• +100 health on kill

Max Upgrade of 1. Only available for Soldier and Demoman's Swords.

Ullapool Caber Tweaks

Caber Extra Dosage

• Armor Piercing: +25%
• Extra Self Damage: 10%

Max upgrade of 32